The present invention relates to apparatus and methods for providing a scalable media delivery system capable of encoding, transmitting and decoding multimedia information in the form of streamed digital data.
Many standardized formats exist for creating digital signals that allow for images and sounds to be recorded, stored, transmitted and played back. Such formats include the MPEG format for digital video, VRML format for 3-D graphics and MPEG and WAV formats for digital audio. Each of these formats is capable of storing sufficient information with respect to a particular image or sound that allows for extremely accurate reproduction of the image or sound.
Despite the fact that these formats allow for conceptually distortion free reproduction of images and sounds, limitations in the computational power of computer systems and network bandwidth limitations prevent reproductions that are as accurate as desired while meeting real time constraints. For more compact and distortion free reproduction, larger quantities of data and/or faster processing is typically required. Accordingly, the digital information that is typically encoded in a given format provides less than optimum resolution so as not to exceed the computational power for decoding available in an xe2x80x9caveragexe2x80x9d computer system and the network bandwidth limitations. Unfortunately, however, computing systems having computational power and available bandwidth that is greater than xe2x80x9caveragexe2x80x9d cannot use the extra computational power they contain and available bandwidth to reproduce images and sound with even greater performance and clarity, since the originally encoded signal contains no further information with which to obtain this greater resolution.
Conversely, if the digital information that is encoded in a given format that provides optimum resolution when being decoded by a high end computer system, other xe2x80x9caveragexe2x80x9d computer systems are unable to decode all of this additional digital information in real time and, therefore, will be unable to reproduce any sound or image at all.
Accordingly, there is a need to for a method and apparatus that allows for the high-end computer systems to decode as much digital information as possible so that they can reproduce images or sounds with optimum resolution for high performance computer systems at the available bandwidth and also provide for xe2x80x9caveragexe2x80x9d or low-end computer systems that receive lesser amounts of information corresponding to their performance capabilities, as well as taking into consideration bandwidth limitations. Thus, for all of these systems, there is the need to receive digital information that is matched to the computational power available.
Further, there is the need for servers to be able, in real time, to determine the amount of digital information to transmit and then transmit this digital information while minimizing the computational power required to perform such operation.
It is, therefore, an object of the present invention to provide a method and apparatus for reproducing sounds and/or images with a resolution that is optimized to the capabilities of the client computer that is decoding previously encoded sounds and/or images.
It is also an object of the present invention to provide a method and apparatus for encoding digital data representing sounds and/or images as base streams and additive streams of digital data.
It is another object of the present invention to provide a method and apparatus for transmitting base streams and a desired number of additive streams of digital data from a stream server to a client computer based on a profile obtained from the client computer.
It is a further object of the present invention to provide a method and apparatus for decoding base streams and additive streams of digital data to allow for accurate reproduction of sounds and images.
It is a further object of the present invention to provide a method and apparatus that allows for variation in resolution of different media forms so that the quality of a media form such as sound can be increased at the expense of the quality of another media form, such as picture image, according to the desires of the user.
It is a further object of the present invention to provide a method and apparatus that allows minimal processing by the server to achieve the objects recited above.
In order to obtain the objects recited above, among others, the present invention provides an apparatus and method for encoding, storing, transmitting and decoding multimedia information in the form of scalable, streamed digital data. A base stream containing basic informational content and subsequent streams containing additive informational content are initially created from standard digital multimedia data by a transcoder. Client computers, each of which may have different configurations and capabilities are capable of accessing a stream server that contains the scalable streamed digital data. Each different client computer, therefore, may access different stream combinations according to a profile associated with each different client computer. Thus, the streams accessed from the server are tailored to match the profile of each client computer so that the best combination of streams can be provided to maximize the resolution of the 3D, audio and video components. Since different stream combinations can be accessed, this advantageously allows for the various combinations of content and resolution that are tailored to match that of the specific client computer. If desired, however, the profile can be further adapted to increase the resolution of certain characteristics, such as sound, at the expense of other characteristics, such as video.